187.] [Footnote 64: See those evolutions admirably well explained by M.
Guichard Nouveaux Memoires, tom.i.p.

141--234.] Such were the arts of war, by which the Roman emperors defended their extensive conquests, and preserved a military spirit, at a time when every other virtue was oppressed by luxury and despotism.

If, in the consideration of their armies, we pass from their discipline to their numbers, we shall not find it easy to define them with any tolerable accuracy.

We may compute, however, that the legion, which was itself a body of six thousand eight hundred and thirty-one Romans, might, with its attendant auxiliaries, amount to about twelve thousand five hundred men.

The peace establishment of Hadrian and his successors was composed of no less than thirty of these formidable brigades; and most probably formed a standing force of three hundred and seventy-five thousand men.
Instead of being confined within the walls of fortified cities, which the Romans considered as the refuge of weakness or pusillanimity, the legions were encamped on the banks of the great rivers, and along the frontiers of the barbarians.